Open
Description
The type_check_mode_ field of LocalVariable is initialized to kDoTypeCheck, which is a safe default. It keeps this conservative value in many cases where it could be given a more precise value. Only covariant parameters ever need to be checked, but the default often stays even for non-parameters.
A more precise value here could also enable a cleaner and perhaps more precise solution to #43464 than the one in https://dart-review.googlesource.com/c/sdk/+/164500.